018-turtle/docs/milestones/mil-003-shapes-and-random-color.md

Milestone 003: Shapes and Random Color

Metadata

Key	Value
ID	MIL-003
CrossReference	BC-001
Language	en
Domain	it

Version History

Date	Status	Author	Reviewer	Change	Commit
2026-10-07	Accepted	Jens Tirsvad Nielsen	S01	Initial version	4b3391b

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Purpose

This milestone decides whether Turtle Challenge 3 (draw different shapes, triangle to decagon, in random colors) works and whether the random_color helper from the tuple lecture is correct, because the random walk and the spirograph of the last milestone both depend on it.

Deliverable

The mil-003-shapes-and-random-color branch, opened as one pull request, containing random_color (an red, green and blue (RGB) tuple), the color palette constant, draw_shape, draw_shapes, their tests, and the shapes challenge in the command line.

Go / No-Go Criteria

#	Criterion (objectively checkable)	Go	No-Go
1	random_color returns a tuple of three integers, each from 0 to 255 inclusive, and is repeatable with a seeded random generator	All three properties hold in tests	Any property fails
2	draw_shape(pen, num_sides) turns 360 / num_sides degrees after each of num_sides sides of 100 units	Recorded moves match for 3 to 10 sides	Any recorded move differs
3	draw_shape rejects fewer than 3 sides with ValueError	The error is raised	No error, or another exception type
4	draw_shapes draws the shapes with 3 to 10 sides, each in a color chosen from the palette in constants.py	Eight shapes, each with a palette color	Any shape missing or off palette
5	python -m turtle_challenges shapes opens a window and draws to completion on Windows PowerShell	S01 confirms in the review record	It fails
6	python -m pytest, ruff check ., ruff format --check ., mypy and doxygen Doxyfile	All exit 0 with 0 Doxygen warnings	Any fails or warns
7	Review record against QC-PY-001	Verdict Go	Go-with-conditions or No-Go

Dependencies

Depends on	Reason
MIL-002 accepted	Needs the Pen protocol, the fake turtle and the command line entry point

Traceability

Business Case objective / KPI / user story	Reference
Challenge 3 and the random_color helper run	O1 in BC-001
Drawing logic separate from the window	O2 in BC-001
Source documented with Doxygen	O5 in BC-001

Ownership

Role	Stakeholder ID (SA)
Owner	S01
Approving reviewer	S01

Target Date

2026-10-17 — the third milestone, leaving four days for the last milestone before the plan ends on 2026-10-21 (Constraints in BC-001).

Tasks

#	Task	Summary	Needs its own Use Case/User Story?	Reference
1	Implement random_color	Implement random_color(rng) in colors.py: three random integers from 0 to 255 returned as a tuple (immutable, so it is safe as a constant-like value). It accepts an optional random.Random so tests can seed it. The upper bound comes from constants.py.	No
2	Add the color palette constant	Add the lecture's list of named colors to constants.py as a tuple (for example CornflowerBlue, DarkOrchid, IndianRed, DeepSkyBlue, LightSeaGreen, wheat, SlateGray, SeaGreen) and a helper that picks one with random.choice.	No
3	Implement draw_shape	Implement draw_shape(pen, num_sides, side_length): the turn angle is 360 divided by the number of sides, repeated for each side with a for loop. Fewer than 3 sides raises ValueError.	No
4	Implement draw_shapes	Implement draw_shapes(pen, rng): loop over 3 to 10 sides, choose a palette color for each shape and call draw_shape. The range bounds are constants.	No
5	Add tests for random_color, draw_shape and draw_shapes	Test the tuple type and range of random_color, repeatability with a seed, the turn angle and side count for every shape from 3 to 10 sides, the ValueError for fewer than 3 sides, and the palette use of draw_shapes.	No
6	Register the shapes challenge in the command line	Add shapes to the choices of python -m turtle_challenges and to the --help text, with a test of the argument parsing.	No
7	Review milestone 003 against QC-PY-001	Review the code and tests against QC-PY-001, record the result as an RC-* and update the instance in the traceability matrix.	No

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